Lightwave communication systems strive for maximum transmission capacity by spacing optical channels as closely as possible, typically a few nanometers or less. However, any drift in the lasing wavelength readily causes the signals from one optical channel to cross into another. As such, lightwave communication systems typically use laser modules which employ external gratings to stabilize the lasing wavelength at a desired value. In this latter case, although the laser housed in the module resonates over a range of wavelengths, the external grating confines or so-called "locks" the laser to operate at a single desired wavelength. This arrangement has the additional benefit that the linewidth of the laser's output is narrowed considerably after passing through the grating.
The above locking mechanism, however, only works over a particular range in temperatures, known as the laser module's "locking range." Traditionally, this locking range is designed to match the span in temperatures for the desired application. It has been observed that the locking range, however, varies from one module to another. Accordingly, it would be desirable to provide for a method to eliminate, or at least minimize, the variations in the locking range of such laser modules.